Grass Seed Calculator: How Much Seed Do I Need?
Calculate pounds, bags, leftover seed, and cost for a new lawn or overseeding project.
Use this calculator to turn your lawn area and seeding rate into the pounds of grass seed you need, the number of bags to buy, leftover seed, and optional cost. Choose a grass type for a typical planning rate or select “Use the rate on my seed bag” for the most accurate result.
How the grass seed calculation works
The formula is lawn area ÷ 1,000 × seeding rate = pounds of seed. For example, a 2,000 sq ft lawn at 5 lb per 1,000 sq ft needs 10 lb of seed. The calculator then rounds up to whole bags and shows how much seed will remain.
Rates vary by species, seed coating, climate, and whether you are establishing or overseeding. Treat the preset as a planning estimate and use the coverage rate printed on your bag when available.
Typical grass seed rates per 1,000 sq ft
| Grass type | New lawn | Overseeding estimate |
|---|---|---|
| Turf-type tall fescue | 7 lb | 4 lb |
| Kentucky bluegrass | 2.5 lb | 1.5 lb |
| Perennial ryegrass | 4.5 lb | 4 lb |
| Fine fescue | 4.5 lb | 2.5 lb |
| General lawn seed mix | 5 lb | 3 lb |
Planning rates use the midpoint of university extension recommendations where available. Your seed label is the final authority, especially for coated seed and blends.
How to measure an irregular lawn
Split the lawn into simple rectangles, measure each section, and add their square footage. For a circle, multiply the radius by itself and then by 3.14. Subtract large areas that will not be seeded, such as a patio, driveway, or garden bed.
Tools you'll need
- Broadcast or drop spreader
- Steel rake
- Lawn roller (optional)
- Straw or seed blanket for cover
- Hose with a gentle sprinkler
Step by step
- Choose the right seed Match seed to your climate and sun — cool-season blends (fescue, rye, bluegrass) for northern lawns, warm-season (bermuda, zoysia) for the south.
- Prep the seedbed Loosen and rake the top 1/4–1/2" of soil so seed can nestle in and make contact — seed on hard ground just feeds the birds.
- Spread at the right rate Use the calculator and the bag rate — heavier for a new lawn, lighter for overseeding. Half the seed one direction, half crosswise for even coverage.
- Rake in and cover Lightly rake or roll so seed is barely covered (about 1/4"), then add a thin straw or seed-blanket cover to hold moisture.
- Keep it moist until it germinates Water lightly once or twice a day so the top stays damp until seedlings are up, then taper to deeper, less frequent watering.
Common mistakes
Safety
- Mind your footing on slopes when spreading.
- Keep seed treated with fertilizer/pesticide away from kids and pets per the label.